Sound-producing device



Feb. 19, 1929. 1,702,437

I J. s. HlGH SOUND-PRODUCING DEVICE Filed May 27, 1926 Fad iffy/2. 45-

INVENTOR July? 5. ///';b

' ATT'ORNEY Patented Feb. 19, 1929.

UNITED STATES PATENT OFFICE.

JURJEN S. HIGH, OF WILKINSBURG, PENNSYLVANIA, ASSIGNOR T0 WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A. COREPORATION OF PENNSYLVANIA.

SOUND- PRODUCENG DEVICE.

Application filed May 27,

-My invention relates to sound-producing devices and it has particular reference to means for improving the quality of the sound produced.

At the present time the majority of the socalled loud speakers used for the reproduction of radio programs and public addresses and for analogous purposes, may be divided into two main classes, namely, those in which a diaphragm is caused to vibrate by external actuating means and those in which the diaphragm itself carries a coil through which passes the varying current, representing the sound to be reproduced. Devices of neither type give entire satisfaction, and I have discovered by research and experiment that the principal causes of poor quality out-- put in devices of the first mentioned type, are abrupt discontinuities, such as changes in the mass or stiffness in the physical characteristics of the train of mechanism between the actuating means and the diaphragm, and the setting up of parasitic vibrations, not truly representative of the sound-currents in the latter due to bending strains imparted thereto by movements of the actuating means.

It is, accordingly, an objectof my inven-' tion to provide a sound-reproducing system in which there will be no objectionable discontinuities in physical characteristics be tween the diaphragm and the actuating means.

Another object of my invention is to provide a connector to be used between the dia phragm and the actuating means that will form therewith a composite body, the physical characteristics of which vary progressively and continuously from the character: istics of the diaphragm per se to those of the actuating means.

Another object of my invention is to provide a connection between the actuating means and the diaphragm of a loud speaker which will not permit the generation, in the latter, of parasitic vibrations setup by torsional or bending forces.

A further object of my invention is to provide an inexpensive form of connector to be used between the actuating means and the diaphragm of a loud speaker.

A still further object of my invention is to provide a device for progressively strength 1926. Serial No. 111,932.

ening the junction between a diaphragm made of comparatively flexible material and a connector which is rigid in character.

To attain these objects and others which will be more specifically brought out later, I so construct the connection between the actuatng means and the diaphragm of a loud speaker, that it has considerable longitudinal rigidity and yet, at the same time, offers but little resistance to bending moments applied at the end thereof which is in contact with the actuating means. At the same time, I provide also, between said connect-ion and the diaphragm, an intermediate element which has a portion that is weakened progressively from its junction with the con nection, toward the area at which it is at tached to the diaphragm. More specifically, I prefer to make the connection referred to in the form of a. rod, pyramid or cone, at one end of which is located a portion of comparat'vely great flexibility. he intermediate element, referred to as being provided between the connection and the diaphragm,

may be made of metal having a star-like form, and the rays of the star may be used for attaching the element to the diaphragm.

Referring now to the drawings and to the following description from which a more complete understanding of my invention may be had:

Figures 1 and 2 are elevational views of a preferred form of my connector.

Figs. 3 and 4 are elevational views of a modified form of my connector.

Figs. 5 and 6 are elevational views of further modified forms of connectors.

Fig. 7 is a top View of a modified type of connector embodying a pivoted bearing. 7

Fig. 8 is a sectional view taken along line VI1IVI1I of Fig. 7

Figs. 9 and 10 are elevational views, partly in perspective, of a combined connector and intermediate element- Figs. 11 and12 are, elevational views,part-- ly in section,- of a modified type of combined connector and intermediate element.

Fig. 18 is a sectional view, on azlarger scale, of the lower portion of the device shown in Fig. 11.

Fig. 14 is a top plan view of modified form of intermediate element.

Figs. 1 and 2 show a connector 1 made of a single piece of sheet metal having a flattened portion 2 which may be soldered to, or otherwise ailixed in, one end of an armature 3. The connector is provided, at its lower end, with depending fingers at adapted to be bent alternately inside and outside of an intermediate element 5, and to be affixed thereto.

Figs. 3 and a illustrate a connector closely analogous to that shown in Figs. 1 and 2, being also made from a single piece of sheet metal so rolled as to form a cone 6. The upper portion 7 of the cone is clamped, soldered or otherwise aflixed to an armature 8, and the lower portion of the cone is provided with fingers 9, analogous to fingers 4: of Figs. 1 and 2. Closely adjacent to the point where the connector 6 is attached to the armature 8, a portion of the material is cut away, leaving a single flexible section 10 which is flattened.

The connector shown in Fig. 5, is formed of a single piece of rigid material 12 provided with screw threaded lugs 18 and let, at the ends thereof, and having a flattened portion '15, near the lug 13.

The connector illustrated in Fig. 6 is analogous to that shown in Fig. 5 and is formed of a single piece of metal 17 pro vided with screw-threaded lugs 18 and 19 at opposite ends thereof. This connector is approximately conical in shape, the portion 20 adjacent lug 18 being made comparatively flexible.

The connector shown in Figs. 7 and 8, comprises a stirrup-shaped element 22, provided with hearing openings 23, in which is seated an element 21- allixed to an armature 25 by means of bolt 26. The stirrup-shaped element is clamped by rivets 27 or otherwise aflixed to a diaphragm or intermediate element indicated at 28.

Figs. 9 and 1() illustrate a combined connector and intermediate element. In these figures, a rigid connector 20, having a flexible portion 31 ailixed to an armature 82, has integral therewith an intermediate element 33 having a plurality of projections 3 1. A dia phragm 35 is cemented, or otherwise affixed, to the projections 34, which may be positioned alternately within and without the apex of the cone.

Figs. 11, 12 and 13 illustrate a combined connector and intermediate element somewhat analogous to that shown in Figs. 9 and 10, but made in separate parts for convenience in manufacture. A connector 40, formed of a single sheet of material folded upon itself to form a frustrum of a cone, has, at one end, a flexible element 41 solderedor otherwise affixed thereto. The element 41 is provided with a threaded portion 42 which passes through an opening in an armature is and is clamped in position by a nut 45. Seated within the lower end of the element 40, is a cup-shaped element 16 centrally provided with a lug 47 having a threaded opening therethrough. An intermediate member 48, provided with radial fingers 49 and having a central opening 50, is clamped to the connector by means of a bolt 52 which passes through the opening in the cupshaped member and the opening in the intermediate member 18. The intermediate member -18 is cemented, or otherwise attached, to a diaphragm 53.

Fig. 14 illustrates a modified form of the intermediate member 48 shown in Fig. 11 and comprises a metallic cup 55 provided with a central opening 56, the cup progressively decreasing in thickness from the central opening 56 toward the periphery 57. It is further provided with a plurality of openings 58 extending entirely therethrough and progressively weakening the cup from the central portion toward the periphery 5'7. The purpose of these openings and of the decrease in stiffness will be explained later.

In my copending application, Serial No. 91,738, tiled March 2, 1926, I have explained that it is \uidesirable to have an entirely rigid connection between the magnetic actuating means and the diaphragm of a loud speaker. I have, in that application, disclosed and claimed. a connector which will. transmit motion along its axis from the actuating means to the diaphragm but which will not transfer bending forces originating in the actuating means. By eliminating these bending forces, the quality of the sound reproduction is greatly improved, and, by my present invention, a further improvement is gained by modifying both the connector and the junction of the connector with the diaphragm,

per se.

In the drawings, Figs. 1 to 6, inclusive, 1 have. illustrated a connector which isso constructed that it is rigid in the direction in which motion is to be transmitted, yet has a portion which is to a certain extent flexible. The flexible portion of the connector serves to prevent angular movements of the actuating means,- or armature, from being trans mitted through the connector, as a whole, to the diaphragm. to setup undesirable vibrations therein.

In the forms of my device, illustrated in Figs. 1, 2 and 4, I construct the connector by bending or stamping a single piece of sheet metal into a substantially cone-shape or pyramid-shape element, having maximum rigidity along its axis. To provide the fiexilt le portion, I may either leave a free end ofthe material, as shown in Fig. 1, or I may remove a portion of the material, asshown in Fig. i. Both of thesemodifications provide a comparatively flexible portion closely adjacent the driving member or armature.

Figs. 5 and 6 illustrate forms of connectors which are closely analogous to those shown in Figs. 1 to 4, both being machined from a iii single rod of materialand both having a flexible portion formed by the removal of the material itself.

The connectors thus far described have been applied to horn speaker diaphragms. They have also been found particularly valuable when used in connection with large coneshape diaphragms made of paper, parchment or analogous deformable material. lVhen paper has been employed as the diaphragm material, I have found it very desirable to avoid abrupt discontinuities in the physical characteristics of the vibrating system considered as a whole. In other words, it is much better to have the relatively thin diaphragm attached to the rigid connector by means of an intermediate element which pro gressively and gradually increases in stiffness from that portion nearest the diaphragm toward that portion which is fastened to the connector.

In the preferred form of my invention, the intermediate element is either provided with a plurality of fingers, as shown in Figures 9 and 11, or is progressively weakened toward the periphery by removing a portion of the material, as shown in Fig. 14. In both of these forms, the stiffness of the element continuously increases from the periphery toward the center.

The connector and intermediate element may, if desirable, be constructed of a single piece of sheet metal rounded or otherwise formed, as shown in Figs. 9 and 10.

In practicing my invention, any one of the various types of connectors shown in Figs. 1 to 8 may be employed with either the starshape intermediate element or the perforated element shown in Fig. 14.

I may also construct the assembly as shown in Fig. 11, in which the flexible portion of the connector, the rigid portion, and the interniiediate elements are separately manufactured and later joined together by means of solder, bolts, or analogous fastening devices.

By eliminating a sharp line of demarcation between the material of the diaphragm and the material of the connector, parasitic vibrations, due to deflection, are avoided, and

. the quality of the sound output is greatly improved. Such reflections always tend to occur at the junction of two media having different densities, when an attempt is made to transfer vibrations from one medium to the other. These parasitic vibrations are partials which are very unpleasant to the ear and which seriously interfere with the quality of the sound being reproduced.

I have further discovered that, for best results, the star-shape intermediate element should have three, live, seven, eleven, or a higher prime number of rays. An element having such number of rays prevents, to a large extent, separate portions of the diaphragm from vibrating with respect to the diaphragm as a whole and the consequent undesirable emphasizing of certain sound frequencies. Such partial vibration I term nodal vibrations.

If more convenient from a manufacturing standpoint, the reinforcement of the dia phragm may be formed in the diaphragn'i material itself or may be an entirely separate: element. In such event, a alain cup may be substituted forthe star-shape or intermediate element I have described above.

I also conten'iplate constructing the cup of a material such as rubber, so forming it that its modulus of elasticity changes from a com paratively high value at the point to which the intermediate connector is aiflxed. to a very low value at the edges of the flaring portion. Such a change in flexibility may be 0 tained either by a proper shaping of the rubber itself or it may be influenced by differentially distributing sulphur or analogous material throughout the body of the cup before vulcanization.

Although I have illustrated and described herein a plurality of specific embodiments of my invention, I am fully aware that many other modifications will suggest themselves to those skilled in the art. I do not intend, therefore, to be limited except in so far as is necessitated by the prior art and as indicated by the following claims.

I claim as my invention:

1. In a sound-producing device, a driven member, a driving member and means comprising a connecting device having a rigid portion and a flattened flexible portion for transmitting only rectilinear mechanical movement from said driving to said driven member.

2. In a sound-producing device, a driving member, a driven member, and means, comprising a rigid elongated portion and a flattened, flexible portion for transmitting mechanical motion from the driving member to the driven member.

3. In a sound-producing device, a diaphragm, driving means, connecting means therebetween' comprising a longitudinally rigid portion, a flexible portion and a portion having progressively decreasing flexi bihty.

l. In a sound-producing device, a diaphragm, driving means, connecting means therebetween having a flexible portion adjacent the driving means, a portion of graduated flexibility adjacent the diaphragm and a rigid intermediate portion.

5. In a sound-producing device, a diaphragin of flexible material, driving means, a connection to said driving means having a rigid portion and means interposed between said connection and said diaphragm, whereby an abrupt change between the rigidity of the connection and the flexibility of the diaphragm is avoided.

6. In a sound-producing device, a diaphragm, actuating means attached thereto and means for progressively decreasing the effective flexibility of the diaphragm toward the point oi. attachment of the driving means.

7 A device for connecting a diaphragm to an actuating means comprising a non-flexible portion and portions of gradually increasing flexibility radiating therefrom.

8. A device for connecting a diaphragm to actuating means comprising a non-flexible central portion. and a marginal portion the flexibility of which increases gradually and progressively in directions away from the central portion.

9. A sound-producing device comprising a diaphragm, actuating means for said diaphragm having a rigid portion and connector means associated with said diaphragm, said means having a non-flexible central portion and portions of increasing flexibility radiating therefrom, the central portion of said connector being attached to the actuating means.

10. A sound-producing device comprising a flexible diaphragm and actuating means therefor having a non-flexible portion, a connecting device uniting the diaphragm to the actuating means and forming therewith a composite body having mechanical characteristics which gradually change from those of the diaphragm per se to those of the nonflexible portion oi the actuating means.

In testimony whereof I have hereunto subscribed my name this 18th day of May, 1926.

J URJEN S. HIGH. 

